Given the rapid advances of human genome research, professionals and the public expect that the near future will bring us, in addition to understanding of disease mechanisms and refined and reliable diagnostics, therapies for many devastating genetic diseases.
While it is hoped that for some (e.g., metabolic) diseases, the improved insights will bring easily administrable small-molecule therapies, it is likely that in most cases one or another form of gene therapy will ultimately be required, i.e., the correction, addition or replacement of the defective gene product.
In the past few years, research and development in this field have highlighted several technical difficulties which need to be overcome, e.g., related to the large size of many genes involved in genetic disease (limiting the choice of suitable systems to administer the therapeutic gene), the accessibility of the tissue in which the therapeutic gene should function (requiring the design of specific targeting techniques, either physically, by restricted injection, or biologically, by developing systems with tissue-specific affinities) and the safety to the patient of the administration system. These problems are to some extent interrelated, and it can be generally concluded that the smaller the therapeutic agent is, the easier it will become to develop efficient, targetable and safe administration systems.